Re: [PATCH v6 0/5] kunit: Add support for suppressing warning backtraces

Peter Zijlstra
2026-03-17T11:30:48Z

On Tue, Mar 17, 2026 at 12:20:26PM +0100, Vlastimil Babka (SUSE) wrote:
> > For this iteration, the `__report_bug()` centralized approach was
> > revisited after the discussion in the previous version [1].
>
> Discussion with PeterZ, who is not CC'd here? (did it now for my reply).
>
> > However, again this approach did not work because:
> > - Some warning output is generated directly in the macros before calling
> > the centralized functions (e.g., `__warn_printk()` in `__WARN_printf()`)
> > - Functions in the warning path like `warn_slowpath_fmt()` are marked
> > `__always_inline`, making it difficult to intercept early enough
> > - So, by the time `__report_bug()` is called, output has already been written
> > to the console, making suppression ineffective
> >
> > Current Proposal: Check Directly in the `WARN()` Macros.
> > This avoids the need for function symbol resolution or ELF section
> > modification.
> > Suppression is implemented directly in the `WARN*()` macros.
>
> So does that bloat every warn/bug site (as Peter objected to) or not?
> And is it compatible with x86? I see you modify include/asm-generic/bug.h
> but x86 has its own version of e.g. __WARN_printf ?

Yeah, they done it all wrong again :-(

This should be pushed inside __report_bug() through __WARN_printf with a
new BUGFLAG thing.

So NAK from me on this -- again!